370 The Art of Dyeing. 



The liquid should he carefully poured so that the glass 

 above the liquid surface be preserved dry, the portion 

 of the glass between the edge and the curved line will then 

 be seen to be partially sprinkled, but between the level of 

 the water and the curved line, it becomes wholly wetted 

 thereby, indicating the height to which the fluid had been 

 thrown at the centre of each vibrating arc. The number 

 of undulations in this curve depends on the number of 

 nodes, and both depend on the note produced. 

 {To be continued.) 



Article VI. 



The Art of Dyeing. 



{Continued from page 288.) 



The spots which strong solutions of chloride of lime pro- 

 duce are thoroughly bleached.* Weaker solutions act by 



* There are several other methods of testing chloride of lime ; 1. by determin- 

 ing how much of a solution of indigo in sulphuric acid is decolourized by a given 

 weight of the powder. 2. By means of muriate of manganese, which is thrown 

 down by the bleaching-powder in the state of teroxide ; the weight of teroxide 

 obtained measures the strength of the powder. 3. By the addition of a solution 

 of bleaching-powder to a solution of proto-sulphate of iron, till the smell of chlo- 

 rine begins to be perceived. 4. By means of a solution of arsenious acid, ac- 

 cording to Gay Lussac. The weight of the chloride to be tested may be fixed at 

 154 - 38 °rs. ; and this may be dissolved in water in such a manner that the solu- 

 tion, including the deposit, shall be equal to l - 76 pint. If we take a constant 

 volume of this solution as "61 cubic inch, divided into 100 parts, and pour a solu- 

 tion of arsenious acid in muriatic acid gradually into it ; measured out in the same 

 way until the chlorine be neutralized, the strength of the chloride will be propor- 

 tional to the number of parts of the solution of arsenious acid which the chloride 

 required. If the chloride destroyed 100 parts of arsenious acid solution, then the 

 value of the chloride would be 100° ; if only 80, then its value would be 80°. — 

 Ann. de Chim. lx. 225. 5. Ferrocyanodide of potassium may be substituted for 

 the arsenious acid. This method is due to Gay Lussac, although it has been 

 known in this country for some time as the discovery of an Italian instrument- 

 maker. The solution of this salt has little or no action upon the chloride, until it 

 is rendered acid. To detect the point of saturation, a drop of a solution of indigo 

 is added to the saline solution, which assumes a fine green colour. This colour 

 fades in proportion as the indigo is destroyed, by the progress to saturation. — 

 Ann. de Chim., ib. 6. The proto-nitrate of mercury, when mixed with a solution 

 of common salt, or with muriatic acid, affords a white precipitate of muriate of 

 mercury, which disappears completely, and is changed into chloride by the addi- 

 tion of a solution of chlorine, or chloride of lime, provided the mixture contains a 

 sufficient quantity of free acid to saturate the base of the muriate. — Ann. de Chim., 

 ib. — Edit. 



